Automatic transmission torque converters are often equipped with a clutch to rotatively link a torque converter turbine with a torque converter input shell. Engagement of a clutch pressure plate with the torque converter shell restricts the rotary displacement of the vehicle engine relative to a torque converter output element, eliminating the slip within an automatic transmission torque converter.
The clutch pressure plate is rotatively connected through intermediate elements to the turbine of the torque converter and to the output element of the torque converter, both of which are rotatively fixed to one another. One of the intermediate elements connecting the clutch pressure plate with the output element is a set of springs which compress to allow the clutch pressure plate to be rotatively displaced relative to the turbine and the torque converter output element. Spring compression occurs upon engagement of the clutch pressure plate with the torque converter input shell when they are rotating at different speeds and when the engaged clutch is subjected to transient torsional impulses, such as impulses produced by the engine firing frequency. Clutch engagements and the transmission of transient impulses can induce the clutch pressure plate and the elements rotatively connected to it to rotatively vibrate at a natural frequency relative to the clutch hub and the elements rotatively connected to it.
It is desirable to minimize the amplitude of these vibrations. A common method of minimizing and reducing the magnitude of the vibrations is to apply a rotary frictional load between the clutch pressure plate and the torque converter output element, in parallel with the rotative spring force of the clutch springs. The result is to damp out the vibrations between the clutch pressure plate and the torque converter output element. The rotary frictional load is typically applied by an axial spring force in series with the frictional element.